Choreutidae, commonly known as metalmark moths, are a family of micro-moths with a worldwide distribution. The family is most species-rich in the tropics, and, as is the case for numerous other small tropical invertebrates, much of its richness is still unknown to science (unpublished data). Currently, 406 species of choreutids are described (Nieukerken et al. 2011).

Choreutids are medium-sized micro-moths with wingspans ranging from about one to two centimeters, often with bright colors and iridescent markings on their wings (Diakonoff 1986). They are diurnal with only some species attracted to lights at night (personal observation), making them a fairly rare group in museum collections. In our experience, large-scale rearing projects result in finding more species of choreutids than employing light traps.

Through exactly such efforts over the past 20 years in Papua New Guinea (PNG), the Binatang Research Center (BRC), with a large international group of collaborators focusing on the ecology of herbivorous insects and their host plants (Miller et al. 2003; Craft et al. 2010; Novotny et al. 2010; Hrcek et al. 2011; Hrcek et al. 2013; Miller et al. 2013), the number of known species of choreutids and our knowledge of their biology have greatly increased. One of the many new species of choreutids found in PNG during this project is sufficiently different from all described species that it requires a new genus.

Coincidentally, through separate collecting efforts by David Agassiz in Africa, a related species was discovered in Kenya. Herein these two species, as well as the genus to which they belong, are described and illustrated, and the phylogenetic position of the new genus within the family is discussed.

The shared presence of the terminal black band with white spots in the forewing (arrows in Figs 1, 3) was the first indication that Niveas kone Rota, sp. n. and Niveas agassizi Rota, sp. n. might be related. Initially this relationship seemed unlikely because of the disjunct geographical distribution of the two (Niveas kone being distributed in the Australasian Region and Niveas agassizi in the Afrotropical Region) and because their DNA barcodes did not suggest a close relationship. However, once the similarities in wing venation and female genitalia were noticed, and we included nuclear genes in the analysis with a more extensive choreutid molecular dataset, the results strongly supported the close relationship between Niveas kone and Niveas agassizi.

All material examined is listed in Table 1. Layered photographs of specimens and slides were taken using an Olympus SZX16 microscope with motorized focus drive attached to an Olympus E520 digital camera. The photographs were then combined by using the programs Deep Focus 3.1 and Quick Photo Camera 2.3. The wing venation drawing was made digitally in Adobe Illustrator CS3 overlaid on top of a slide photograph. All images were improved in Adobe Photoshop CS3. Genitalic dissections and terminology follow Rota (2008b).

Field sampling and rearing protocols for the PNG material are detailed in Miller et al. (2003; 2013), Craft et al. (2010), and Novotny et al. (2010). The Plant List website (2010) was used for host plant names. Latitude, longitude, and altitude data for the collecting localities is in Table 2.

The molecular phylogeny dataset included three outgroups and 40 species of ingroup taxa, including two individuals each of Niveas kone and Niveas agassizi totaling 45 terminal units. We analyzed data from eight genes: COI (mitochondrial), CAD, EF1α, GAPDH, IDH, MDH, RpS5, and wingless (all nuclear) (Wahlberg and Wheat 2008). The final alignment was 6187 base pairs long. Molecular sequences for all taxa except Niveas kone and Niveas agassizi are from Rota (2011) and Rota and Wahlberg (2012), and their GenBank accession numbers can be found there. For the specimens of Niveas kone (660733) and Niveas agassizi (Ch_JR44_1), DNA extraction was done from whole abdomens, which were later used for dissection of genitalia. Because the DNA amplification methods described by Wahlberg and Wheat (2008) did not work for obtaining sequences of nuclear genes from these specimens, suggesting that their DNA was too degraded for the standard approach, we used newly-designed primers (Niklas Wahlberg, unpublished) (Table 3) to amplify short fragments of the nuclear genes (see Table 4 for total number of base pairs for each gene fragment amplified and the GenBank accession numbers for fragments longer than 200 base pairs). For sequence storage and manipulation we used the VoSeq application (Peña and Malm 2012). The nexus file with the alignment is available from the Figshare Digital Repository: https://doi.org/10.6084/m9.figshare.811841

Both maximum likelihood (ML) and Bayesian phylogenetic analyses were performed. ML analysis of unpartitioned data was conducted using RAxML blackbox available online (Stamatakis et al. 2008) with the GTR+G model and 100 bootstraps. Bayesian analysis of data partitioned using the program TIGER (Cummins and McInerney 2011) as described in Rota and Wahlberg (2012) was carried out in MrBayes v. 3.2 (Ronquist et al. 2012) for 10 million generations with one cold and three heated chains, sampling trees every 1000 generations. The analyses were run on the freely available Bioportal server (University of Oslo, Norway). The convergence was assessed by examining plots of log likelihoods and all model parameters using Tracer v.1.5 (Rambaut and Drummond 2007), as well as potential scale reduction factors and split frequencies, both reported by MrBayes. Branch support is expressed as Bayesian posterior probability (PP) and maximum likelihood bootstraps (ML BS).

DNA barcode sequences (COI) for Niveas kone (24 specimens) and Niveas agassizi (2 specimens) were obtained at the Biodiversity Institute of Ontario, University of Guelph, using their standard methodology (Craft et al. 2010; Hrcek et al. 2011; Wilson 2012). They are deposited in GenBank as accessions listed in Table 1, and their full data including images are in the Barcode of Life Database (http://www.boldsystems.org; see Ratnasingham and Hebert 2007; 2013). These sequences were also analyzed with MrBayes v. 3.2 (unpartitioned dataset, 2 million generations).

The two species of Niveas described herein are superficially quite different, but upon closer examination it becomes apparent that they share a number of morphological features. We consider the following as potential autapomorphies of Niveas: fusion or reduction in R veins in the forewing (Figs 5, 6); presence of round, concave sclerotizations on the A7 sternite in females (arrows in Figs 8, 9); strong lateral sclerotizations at the base of the ductus bursae (triangles in Figs 8, 9); and the presence of a terminal black band with white spots in the forewing (arrows in Figs 1, 3). In all other Choreutinae genera there are five fully-separated radial veins in the forewing; the A7 sternite in the female, as well as the base of the ductus bursae, are evenly sclerotized; and if present, a black terminal band in the forewing lacks white spots.

The split between Niveas kone and Niveas agassizi has presumably happened a long time ago based on the large COI divergence between them and the length of branches in the phylogenetic analysis including the nuclear genes. We considered assigning each species to its own monotypic genus because of their different external appearance, as well as some of the differences in venation and some aspects of female genitalia. It is unfortunate that Niveas agassizi is known from females only as perhaps the morphology of the male genitalia would help clarify the status of this species. However, we believe that Niveas kone and Niveas agassizi being each other’s closest relatives among the currently known species of choreutids is best conveyed by assigning them to a single genus and therefore we opted for this more conservative approach. It is conceivable that other species of Niveas that might bridge this gap in both genetic and morphological variation will be discovered in the future. On the other hand, it is also possible that a new genus will need to be erected to accommodate Niveas agassizi and its currently unknown relatives.